I searched the Irish Family History Foundation's database. It contains 12,000,000 surviving rcds for abt 65% of Irish counties. Rcds are increasingly sparse B4 1840, rare B4 1800. Unless you KNOW the county of origin, the chance that your ancestors' rcds AREN'T in the database is AT LEAST 35%.
For Thomas McGovern B 1862 +/- 4 yrs in Co. Cavan with a father named Francis, I found 2 B rcds: 1858 and 1861.
For Bridget Reilly B 1864 +/- 4 yrs in Co. Cavan, I found 67 B rcds. However, only 3 had a father's name beginning with a "C." These are in 1860, 1863, and 1868. You may have the wrong forename, or there is a transcription error.
For a Francis McGovern and Catherine Prior marriage, I couldn't find matching marriage rcds in Cavan. They either married elsewhere or the rcd didn't survive.
For a Charles Reilly and Mary Freehill marriage, there is 1 M rcd for Mary at any date. This was in 1866 in Bailieborough (PR) parish. The groom's name MAY have been Michael Reilly, not Charles. A view of Mary's rcd may resolve this question. This may have been a mixed marriage.
Google the Foundation's name to lead you to this database. Register, opt to be notified as rcds are added and browse. Pls post your search results to my genforum msg.